The significance of prostaglandins (PG) lies on their ubiquity, high potency and multiple pharmacological effects. The knowledge on PG actions on red cells is limited. It is proposed to evaluate the effects of PG rheological properties of red cells, their phagocytosis and mechanisms of their action. The following studies are proposed: (1) PG effect on cells is mediated by adenyl cyclase-cyclic AMP system and the availability of intracellular Ca2 ion. The latter mechanism and its relative sign-remains to be established. Red cells, which lack adenyl cyclase-cyclic AMP system will be used as a model to evaluate PG effects on CA2 ion metabolism. It is proposed to evaluate PG effects on content and ionic activity of calcium, Ca2 ion fluxes content and fluxes of monovalent cations and ATPase activities involved in Ca2 ion extrusion and active transport of Na and K ions. (2) PGE2 decreased red cell filterability. It is proposed to compare the effects of various PG's on the viscosity and filterability-of red cell suspensions, and evaluate if such changes result from PG induced CA2 ion accumulation. PG binding to red cells and changes in PG and calcium content will be studied in disorders where PG may be involved in red cell injury. These will include (a) disseminated intravascular coagulation, where the liberation of PG with subsequent PG binding to red cells may alter their deformability and potentiate cell injury by adhesion to fibrin strands and (b) immuno-hemolytic anemias, where binding of PG produced by macophages may contribute to decrease in deformability of red cells. (3) PG's have strong chemotatic properties. It will be studied if PG coating of red cells results in their adherence to macrophages or if it accelerates phagocytosis of red cells coated by antibody or lysolecithin.